Conventionally, a so-called active matrix liquid crystal display panel including a thin film transistor (hereinafter also referred to as a “TFT”) over a glass substrate is manufactured by patterning various thin films through a light-exposure step using a photomask as in a manufacturing technique of a semiconductor integrated circuit.
A production technique for efficiently performing mass-production by cutting a plurality of liquid crystal display panels out of one mother glass substrate has been adopted so far. The size of a mother glass substrate has been enlarged from 300 mm×400 mm of the first generation in the early 1990s to 680 mm×880 mm or 730 mm×920 mm of the fourth generation in 2000. Furthermore, the production technique has progressed so that a large number of display panels can be obtained from one substrate.
When the size of a glass substrate or a display panel is small, patterning treatment can be performed comparatively easily by using a photolithography apparatus. However, as a substrate size is enlarged, an entire surface of a display panel cannot be simultaneously treated by performing light-exposure treatment once. Consequently, a method for exposing an entire surface of a substrate to light has been developed as a light-exposure treatment (for example, consecutive light-exposure to one substrate for connecting edges of elements such as a wiring, not to be disconnected at a boundary between the elements). This method is performed by dividing a region where a photoresist is applied into a plurality of block regions, performing light-exposure treatment on every predetermined block regions, and sequentially repeating the treatment (for example, Reference 1: Japanese Patent Laid-Open No. H11-326951).